Encyclopedia of

Exposure to the Elements

Although humans are among the most adaptable of the earth's
creatures with one of the broadest territories of settlement, their
ability to survive extreme temperatures is limited. Death can occur by
exposure to extreme heat or cold. A person who falls through the ice into
water will typically die within twenty to thirty minutes because of heart
standstill or heart fibrillation. By then, his or her internal or core
body temperature will have fallen to approximately 77 degrees Fahrenheit.
Often death is a combination of stresses to the body such as hypothermia
and starvation as in the case of the Donner party, the ill-fated group of
emigrants that was caught in the Sierra Nevada Mountains during the winter
of 1846. The decrease in core body temperature is compensated for by
shivering, constriction of surface blood vessels to direct the blood to
internal organs, and behavioral actions such as increasing voluntary
exercise or putting on more clothes. As hypothermia sets in the rate of
all metabolic processes slows down,
leading to loss of judgment, apathy, disorientation, and lethargy.
Breathing becomes slower and weaker, the heart slows, and disturbances in
cardiac rhythm occur, leading to death. Many symptoms of hypothermia were
evident in the oral and written accounts of the Donner party, adding to
the inability to supplement their rapidly decreasing food supply.

The limits for hot air temperature that one can stand depend on whether
the air is wet or dry. The core temperature of a nude body can remain
within normal range (97 to 99 degrees Fahrenheit) for hours when exposed
to dry air ranging from 55 to 130 degrees Fahrenheit. However, if the
humidity of the air approaches 100 percent or if the person is submerged
in water, the core temperature will rise whenever the environmental
temperature rises above 94 degrees Fahrenheit. The body responds to heat
stress by sweating, dilating surface blood vessels to expose more of the
internal heat to the outside, and behavioral actions, such as removing
clothes. In extreme situations, especially in hot arid environments, the
body can lose enough water and salts in sweat to cause heat exhaustion, a
condition consisting of muscle cramps, impairment of the cardiovascular
system, unconsciousness, delirium, and death. Symptoms of heat exhaustion
are increasing fatigue and weakness, excessive sweating, low blood
pressure, cold, pale, and clammy skin, anxiety, and disorientation. A
person with heat exhaustion can be helped by laying his or her body flat,
or by tipping the head down to increase the blood supply to the brain
while administering small amounts of sugar water to increase blood volume.
Heat exhaustion can be prevented by adequate hydration before, during, and
after physical activity.

Heat stroke (or sunstroke) can be induced by overexertion with prolonged
exposure to a hot, humid environment, at environmental temperatures as low
as 85 to 90 degrees Fahrenheit. In this case the body is unable to sweat
due to the malfunctioning of the thermoregulatory control center in the
brain. Tissue damage to the nervous and cardiovascular systems occurs when
the core temperature rises above 109 degrees Fahrenheit, causing death.
Symptoms of heat stroke may include headache, dizziness, fatigue, and
awareness of the rapidly rising temperature. The person increases his or
her rate of breathing to expel the excess heat and the heart races but the
blood pressure is not affected. Sweating is typically decreased so the
skin is hot, flushed, and usually dry. Treatment is aimed at cooling the
person down and hospitalization is recommended to ensure that the
thermoregulatory control center regains normal functioning. Heat
exhaustion can quickly and unexpectedly lead to heat stroke and death even
of the most physically fit, as was the case with offensive tackle Korey
Stringer, who died in a Minnesota Vikings 2001 summer preseason practice.
Although the body is well equipped to handle normal changes in body
temperature, extreme changes in environmental conditions may not be able
to be compensated for and can lead to irreversible damage and death.